And I'm Steve Inskeep. Here's another reminder that a fast-moving news story can completely change. Prosecutors have dropped the charges against Paul Kevin Curtis. He's the Elvis impersonator first arrested in the case of ricin being sent to U.S. officials, as we reported last week.

Now we're reporting, just as prominently, the change in focus to another Mississippi man's house. NPR's Debbie Elliott has been following this case. She's on the line. Hi, Debbie.

DEBBIE ELLIOTT, BYLINE: Hi, Steve. Good morning.

INSKEEP: Good morning. So what happened?

ELLIOTT: Well, it appears federal prosecutors weren't able to build a case against Curtis, the Elvis impersonator from Corinth, Mississippi. That's in the northern part of the state.

INSKEEP: Mm-hmm.

ELLIOTT: And in a federal court filing yesterday they cited new evidence in the investigation, but they didn't really give us any details about what that evidence might be. Now, this happened while he was in the midst of a hearing that was mysteriously canceled yesterday morning - a preliminary hearing intended to find out what the evidence was against him.

And on Monday at that hearing, an FBI agent had testified that a search of Curtis' home and vehicle did not turn up any evidence of the poison in question, ricin, and that there was no indication that he had ever even researched, you know, how to make the dangerous poison.

INSKEEP: So basically the evidence against him was that his name was on the letters? But he said he was framed; he was set up.

ELLIOTT: Right. That's what his lawyer has said from the beginning - that there was no physical evidence and that possibly he was framed. There were three letters that were all postmarked from Memphis, where a good bit of mail from north Mississippi is processed.

INSKEEP: Mm-hmm.

ELLIOTT: They went to President Obama, Republican U.S. Senator Roger Wicker - who is from a little town just outside of Tupelo - and a local judge there in north Mississippi. All of them were signed: I am KC and I approve this message. Now that is a sign off that Curtis was known to use on Facebook and in letters and elsewhere. Now, as he stood outside of the Oxford federal courthouse yesterday saying he might be rethinking his social media behavior.

PAUL KEVIN CURTIS: I have always signed, for 15 years: This is KC and I approve this video, this is KC and I approve this message. And I did that purposely so word would spread all over the world that when they see my video, when they see something in politics that I am convicted and I stand strong with, they'll go, oh, yeah, the Elvis guy. And so I wanted that connection. But the very connection got me arrested.

ELLIOTT: Now he acknowledges that he understands why federal authorities may have targeted him, given the similarities.

INSKEEP: He says, the right thing that they came and questioned him, but of course there is a dark side to fame, even small fame. He found that out. But where does this leave the investigation? This means there is still somebody out there who sent these letters laced with poison.

ELLIOTT: Right. And yesterday afternoon, just as he was being released from jail, FBI agents apparently took their search to another man's house in Tupelo. They started yesterday afternoon and finished up about 11 o'clock last night, not really saying what they were looking for.

Members of the state's chemical response team were also there. They fanned out into the neighborhood looking through wooded areas and ditches. The man who lives in that house is J. Everett Dutschke. He has told local newspapers and the AP that agents have searched his home and were there a little bit last week. Federal officials have not said anything about him.

We do know that he was also a musician and had a relationship with Curtis, and the two...

INSKEEP: The Elvis impersonator.

ELLIOTT: ...apparently - yes.

INSKEEP: OK.

ELLIOTT: And the two had apparently been in a dispute. His lawyer is saying he's cooperating fully with the FBI and has not been charged. So that's about all we know at this point.